TENDO ACHILLIS. 



251 



septum -wbicli divicles the muscle into lateral halves ; while those froin 



their superficial aspects pass with similar obliquity to the flat tendon 



on the surface of the muscle, the fibres 



placed at the sides forming the lateral Fig. 195. 



borders and part of the deep surface of 



the muscles. Thus the soleus is composed 



entirely of short oblique fibres of from 



one to two inches in length. 



1^ 



Fig. 195. — Deep Postekiok Muscles of the 

 Leg. (A.T.) i 



a, ])oi>]itea\ surface of tlie femur ; i, bare surface 

 of the upper fourth of the fibula, fi'om which the 

 soleus muscle has been removed ; c, malleolus in- 

 tern'us ; d, malleolus externus ; c, tuberosity of the os 

 calcis, vitl] a part of the tendo Acliillis inserted into 

 it, and the plantaris on its inner side ; 1, inner head of 

 the gastrocnemius cut short at its origin ; 2, outer 

 head ; 3, plantaris ; 4, tendon of the semimeni- 

 1)ranosus muscle near its insertion, seen spreading in 

 three portions, viz. , to the inside of the tibia, tow;ads 

 the popliteal fascia, and towards the ligamentum 

 posticum ; 5, tendon of the biceps inserted into the 

 Tiead of the fibula ; 6, popliteus muscle ; 7, upper 

 part of the origin of the soleus from the fibula, cut 

 short ; 7', line of its tibial origin ; between these 

 figures is seen the peiforation in the upper part of 

 the interosseous membrane ; 8, tibialis posticus ; 8', 

 its tendon, passing between the flexor digitorum 

 communis and the tibia ; ,!), flexor digitor.im com- 

 munis ; 9', its teirdon, with that of the tibialis pos- 

 ticus, passing behind the malleolus internus ; 10, 

 flexor longus pollicis ; 10', placed beside its tendon, 

 where it passes over the tiljia and astragalus ; 11, 

 pei'oneus longus j 11', its tendon behiml that of the 

 peroneus brevis, passing down behind the malleolus 

 externus ; 12, peroneus brevis. 



J?clatimti}. — Tlie soleus rests upon the flexor 

 longus pollicis, flexor longus digitoruin, and 

 tibialis posticus muscles, together with tlie pos- 

 terior tibial vessels and nerve, from which, how- 

 ever, it is separated by the deep aponem-osis. 



Vark'tu'f!. — To the soleus an accessory por- 

 tion is occasionally added at its lower and inner 

 part ; this usually ends on the inner side of the 

 tendo Achillis, but it sometimes forms a tendon, 

 attached separately to the os calcis. 



I 1 



'I 



'IL 



The tendo AcMllis. the thickest and 

 strongest tendon in the body, is formed by 

 the union of the flat tendon of the gastro- 

 cnemius with the thicker and more rounded 

 tendon of the soleus. It is from three to 

 four mches long below the point where the 

 muscular fibres of the soleus cease to be 

 attached to it. It is inserted inferiorly into the back part of the 

 tuberosit}' ot the os calcis. A synovial bursa is interposed between the 

 uppei part of the tubeiosity of tlie os calcis and the tendon. 



